1. Field of the Invention
This invention relates to the structural arrangement on the periphery of the shutter device of a single-lens reflex camera.
2. Description of the Prior Art
FIGS. 1 and 2 of the accompanying drawings show, in outline, the structural arrangement of the conventional camera. A photo-taking lens 4, which is a photo-taking optical system, consists of four lens units, including a first lens unit 1, a second lens unit 2, a third lens unit 3 and a fourth lens unit 4. Generally, these lens units are incorporated in an interchangeable lens barrel. The illustrations include a diaphragm 5; and a movable mirror 6 which is swingably disposed within a photo-taking optical path. Under the condition as shown in FIG. 1, a light flux coming from an object through the photo-taking lens units 1 to 4 is guided by the mirror 6 to a view finder optical system. Under a mirror uplifted condition which is not shown, the mirror 6 is retracted from the phototaking optical path to allow the light flux of the object to reach the surface of a film in use. The view finder optical system consists of a focusing screen 7, a pentagonal roof type prism 8 and an eye-piece lens 9. A reference numeral 10 denotes a camera body. An aperture 10a is arranged to determine a film exposing area. A numeral 10b denotes an image forming plane on which the film comes to abut. A focal plane shutter device 11 includes a base plate 11a and a cover plate 11b. Within a space formed between the base plate 11a and the cover plate 11b, there are provided leading and trailing shutter curtains 11c and 11d each of which consists of a plurality of divided blades. These shutter curtains 11c and 11d are arranged to travel downward from above, as viewed in FIG. 1, at a time difference between them corresponding to a given shutter time.
Referring to FIG. 2, the camera body 10 includes a spool chamber 10c and a film cartridge chamber 10d which are formed on the right- and left-hand sides of the camera body. In the spool chamber 10c there is arranged a film winding device including a film take-up spool 12 which forms a film winding transmission system having, for example, a motor as a drive source. The film winding transmission system also includes a sprocket 13 which is disposed close to the aperture 10a. The lateral dimension of the shutter device 11 is arranged to be larger than the opening dimension of the shutter. More specifically, there are provided left and right stowing spaces 11f for the blades forming the leading and trailing shutter curtains 11c and 11dbecause these blades are lengthened for the purpose of preventing them from jumping out of position. A shutter drive unit 11e is arranged to drive the shutter. A reference symbol L1 denotes a light flux which is to be imaged at the center of an image plane; and a symbol L2 denotes a light flux to be imaged at a peripheral part of the image plane.
The conventional single-lens reflex camera, which is arranged as described above, requires the following points: First, the shutter device 11 is disposed in a position nearly abutting on the aperture 10. Second, the full open dimensions of the shutter device 11 must be the same as the opening dimensions of the aperture 10a both in height and in width. Thirdly, the shutter device 11 must have a larger width than its opening width because of the stowing spaces 11f required as mentioned above. These requirements necessitate that the spool chamber 10c, the film cartridge chamber 10d and the sprocket 13, which are components of the camera body, to be approximately aligned side by side with the aperture 10a on both sides of the aperture are arranged away from the aperture 10a to an extent corresponding to the stowing spaces 11f of the shutter device 11. This has caused an increase in the width of the camera body.
Meanwhile, the conventional single-lens reflex camera has been required to satisfy the following various conditions in its light receiving arrangement for light or distance measurement:
(1) The light receiving optical system must be simple in structure and easily adjustable. (2) Must be capable of giving a sufficient light quantity. (3) Must be capable of giving a desired photometric sensitivity distribution.
To meet these conditions (1), (2) and (3), the conventional camera has been provided with the following light receiving arrangement and particularly the following photo-sensitive element arrangement:
(a) The light from the object is arranged to be received from a focusing screen with a photo-sensitive element disposed in the neighborhood of the eye-piece lens of a view finder optical system; (b) the focusing screen of the view finder optical system is obliquely cut and the cut parts are cemented in the middle part thereof to make the cemented face into a half-mirror in such a manner as to guide a portion of the light flux of the middle part of the focusing screen to the photo-sensitive element disposed on one side of the focusing screen; (c) the main mirror, which is arranged to reflect the object light toward the view finder optical system at its lowered position, is arranged to be semi-transmissive at the middle part thereof and a sub-mirror is disposed behind the semi-transmissive part while a photo-sensitive light receiving element is disposed in a position to receive the light of the object reflected by the sub-mirror; and (d) when a photo-taking operation is performed, the light of the object reflected by the film surface is arranged to be received by the photosensitive element which is disposed in front of the film surface.
However, the above-stated conventional arrangements (a) to (d) are incapable of satisfying all of the above-stated conditions (1), (2) and (3). Especially, in carrying out light measurement, it has been difficult to obtain an even photo-sensitivity distribution for the object light received at different areas. In other words, for example, it has been difficult to adequately carry out a split light measuring operation or the like.
Meanwhile, it has been practiced to provide a camera with a data imprinting device. The data imprinting device is incorporated in the back lid of the camera and is arranged to perform imprinting from behind the film. In that instance, a data is imprinted via an antireflection layer (or a backing layer) provided on the reverse surface of the film. However, the degree of difference in sensitivity between the front and reverse surfaces varies with the kind of the film. This results in different densities of the imprint. To solve this problem, there has been proposed an improved method of imprinting the data from the front of the film which has an emulsion layer. In the case of a single-lens reflex camera or the like where a shutter is arranged immediately before the film, however, the density of the data imprint comes to vary with the shutter speed. This has presented a problem.